Post navigation

CITW 9: The Racing Heart

Welcome back to another Clinical Image of the Week from the case files of the Brown EM Residency!

HPI: A 60 year old female presents with palpitations after walking on the beach with friends. She states she was sitting at her favorite clam shack, and felt the onset of a “rapid heart rate”. Thinking she was dehydrated, she drank some water, and her palpitations resolved after five minutes. After returning home, the palpitations recurred, and after 40 minutes she felt “really tired, really washed out”, but at no point had any chest pain, dyspnea, or lightheadedness. She looked “gray” to her husband, so he called 911.

Stable Monomorphic Ventricular Tachycardia

As a general rule of thumb, ventricular tachycardia will have QRS complexes >140 ms, and there should be no p waves proceeding each QRS complex (implying sinus rhythm).

There’s been quite a bit of literature looking at the delineation between ventricular tachycardia and SVT with aberrancy. Lets take a look at some:

Brugada, et al prospectively analyzed 384 patients with VT and 170 patients with SVT (with aberrancy), and came up with the following clinical decision rules:

1: Is there an absence of RS waves in all precordial leads (i.e. is the QRS concordance across all precordial leads the same)? If yes, think VT.
2: Is the R to S interval >100 msec (implying conduction originating in the ventricular myocardium versus conduction pathways)? If yes, think VT.

3: Is there AV dissociation (look for p waves marching out independently or fusion/capture beats, which would imply supraventricular activity independent of the ventricular rate)? If yes, think VT.

4: LBBB or RBBB morphology in the precordial leads (implying use of the conduction pathways, especially if the initial component of the QRS complex is narrow)? If yes, think SVT with aberrancy.

Unfortunately, the Brugada criteria did not fare quite as well in validation studies. Along came the Verecki criteria, which restricted the analysis to lead aVR only. They looked for the presence of an initial R wave (implying conduction moving from the apex of the heart towards the base), the width of an initial R or Q wave >40 msec (implying myocardial conduction versus conduction fibers), and notching on the initial downstroke of a predominantly negative QRS complex. Any 1 of these 3 criteria being positive, was a diagnosis of VT.

Well, by now, most people’s heads were spinning. In an effort to simplify this whole process, the Sasaki rule was devised. They applied both of the above rules to 107 patients with wide complex tachycardias and examined the diagnostic accuracies of each. Their rule was simpler and more accurate than both of the above rules:

Stable? Electric or chemical conversion. You can also safely use adenosine in these patients assuming the rhythm is regular, which will convert a patient in SVT and not harm a patient in VT.

An irregular rhythm with a wide QRS could be WPW. Do not use adenosine in this scenario. Wait, didn’t I already do a post on this? I sure did.

Case conclusion:

The patient received an amiodarone bolus with resolution to sinus rhythm. Cardiology was consulted afterwards and agreed with a VT diagnosis after viewing EKG. The patient was placed on an amiodarone drip and transferred to the CCU where she underwent electrophysiology studies.

Shout out to Dr. Pensa for this case!

The contents of this case were deliberately altered to protect the identity of the patient. All content in this report are for educational purposes only. The patient consented to the use of these images.